Indeed, FDA (Food and Drug Administration)'s Policy Statement for Development of New Drugs recommends “that the pharmacokinetic profile of each isomer should be characterized in animals and later compared to the clinical pharmacokinetic profile obtained in Phase I” drug testing. Thus, the demand for racemic switch technologies to produce each pure isomer has been rapidly increased in recent years.
Aryl propionic acids are non-steroidal anti-inflammatory drugs and known as profen drugs such as ibuprofen, ketoprofen, naproxen, flurbiprofen, fenoprofen, suprofen and the like. It is generally believed that (S)-profens have higher pharmacological effects of the racemic mixture of profens bearing at least one benzene ring. A method for preparing optically pure (S)-profen drugs involves the conversion of a racemic mixture of profen ester to optically active profen carboxylic acid by reacting with a stereoselective chiral enzyme.
However, it has been recently reported that (R)-enantiomers of profens also exhibit therapeutic effects. Particularly, U.S. Pat. No. 6,255,347 discloses that (R)-enantiomer of ibuprofen may be used as a prophylactic and therapeutic agent in the treatment of diseases such as cancers, Alzheimer's and Alzheimer's-related diseases. In the method for preparing (R)-enantiomer of aryl propionic acid, a racemic mixture of aryl propionic acid is treated with an esterase to produce an ester of (S)-enantiomer of aryl propionic acid and un-reacted (R)-enantiomer of aryl propionic acid is recovered.
Further, inventors of the present invention have identified the presence of a stereoselective hydrolase activity in Pseudomonas sp. and its use in the preparation of (S)-profen (KR Patent Application No. 2000-02565). U.S. Pat. No. 6,201,151 discloses a process for preparing an optically active (S)-aryl propionic acid by hydrolyzing racemic thioester of aryl propionic acid in the presence of a (S)-stereoselective lipase. KR Patent Application No. 2001-0044879 discloses a process for preparing optically pure acetylmercaptoisobutylate using an esterase isolated from Pseudomonas aeruginosa. KR Patent Application No. 1996-14399 discloses a process for preparing optically pure aryl carboxylic acid stereoselectively from a racemic mixture of α-aryl carboxylic acid using S-(-)-α-ethyl benzylamine. KR Patent Application No. 1999-0042314 discloses a process for preparing optically active carboxylic acids and esters as drugs for the treatment of hypertension using a hydrolase isolated from Klebsiella pneumoniae. U.S. Pat. No. 5,516,690 discloses that (S)-ketoprofen can be produced with a purity greater than 95% using isolated Trichosporon laibacchii. 
However, the above-mentioned enzymes were not shown suitable for the selective production of optically pure (S)- or (R)-enantiomers of aryl propionic acid and there has been no report on mass production of those enzymes.